132 research outputs found
Evaluation of flagellum-related proteins FliD and FspA as subunit vaccines against Campylobacter jejuni colonisation in chickens
AbstractCampylobacter is the leading cause of food-borne diarrhoea in humans in the developed world and consumption of contaminated poultry meat is the main source of infection. Vaccination of broilers could reduce carcass contamination and zoonotic infections. Towards this aim, we evaluated recombinant anti-Campylobacter subunit vaccines based on the flagellum-capping protein FliD and the flagellum-secreted protein FspA as they are immunogenic in chickens and the flagellum is vital for colonisation. In three studies, a recombinant FliD vaccine induced a transient but reproducible and statistically significant decrease of c. 2log10CFU/g in caecal colonisation levels at 49 days post-primary vaccination on the day of hatch. Levels of serum IgY specific to FliD positively correlated with caecal bacterial counts in individual birds, indicating that such antibodies may not play a role in protection. The data add to the limited repertoire of candidate antigens for the control of a key foodborne zoonosis
Segmentation of Subtraction Images for the Measurement of Lesion Change in Multiple Sclerosis
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
Outcome of laparoscopic upper pole heminephroureterectomy in children: A two-centre experience
Green index in semigroups : generators, presentations and automatic structures
The Green index of a subsemigroup T of a semigroup S is given by counting strong orbits in the complement S n T under the natural actions of T on S via right and left multiplication. This partitions the complement S nT into T-relative H -classes, in the sense of Wallace, and with each such class there is a naturally associated group called the relative Schützenberger group. If the Rees index ΙS n TΙ is finite, T also has finite Green index in S. If S is a group and T a subgroup then T has finite Green index in S if and only if it has finite group index in S. Thus Green index provides a common generalisation of Rees index and group index. We prove a rewriting theorem which shows how generating sets for S may be used to obtain generating sets for T and the Schützenberger groups, and vice versa. We also give a method for constructing a presentation for S from given presentations of T and the Schützenberger groups. These results are then used to show that several important properties are preserved when passing to finite Green index subsemigroups or extensions, including: finite generation, solubility of the word problem, growth type, automaticity (for subsemigroups), finite presentability (for extensions) and finite Malcev presentability (in the case of group-embeddable semigroups).PostprintPeer reviewe
Recommended from our members
HIV testing is associated with increased knowledge and reductions in sexual risk behaviours among men in Cape Town, South Africa
HIV testing benefits those who test positive, allowing them to receive treatment, but the benefits for those who test negative remain controversial. We evaluated the impact of testing on HIV knowledge and sexual risk among men in South Africa. Men were recruited from townships outside Cape Town and completed a survey that assessed testing history, knowledge, and sexual behaviours. Among the 820 participants, 516 (63%) reported being tested (82% tested negative, 6% tested positive, and 12% unknown). Compared to those who had never been tested for HIV, men who tested for HIV were more knowledgeable about HIV transmission, but did not differ on sexual risk behaviour. Knowledge moderated the effect of testing on sexual risk such that men reported fewer sexual partners (incidence rate ratio (IRR) = 0.91, 95% CI = 0.84, 0.98) and fewer unprotected anal sex events (IRR = 0.81, 95% CI = 0.66, 1.00) if they had been tested for HIV and were knowledgeable about HIV transmission. For men testing HIV-negative, knowledge predicted fewer sexual risk behaviours. Previous HIV testing is associated with enhanced knowledge,
which moderates sexual risk behaviour among South African men living in Cape Town. Results suggest that HIV testing may increase knowledge and lead to reductions in sexual risk even when results are negative.
Recommended from our members
Heterosexual anal intercourse and HIV infection risks in the context of alcohol serving venues, Cape Town, South Africa
The most efficient sexual behavior for HIV transmission is unprotected receptive anal intercourse. However, it is unclear what role heterosexual unprotected anal sex is playing in the worlds worst HIV epidemics of southern Africa. The objective is to examine the prevalence of heterosexual unprotected anal intercourse among men and women who drink at informal alcohol serving establishments (shebeens) in South Africa. Cross-sectional surveys were collected from a convenience sample of 5037 patrons of 10 shebeens in a peri-urban township of Cape Town, South Africa. Analyses concentrated on establishing the rates of unprotected
anal intercourse practiced by men and women as well as the factors associated with practicing anal intercourse. We found that 15% of men and 11% of women reported anal intercourse in the previous month, with 8% of men and 7% of women practicing any unprotected anal intercourse. Multiple logistic regression showed that younger age, having primary and casual sex partners, and meeting sex partners at shebeens were independently associated with engaging in anal intercourse. Mathematical modeling showed that individual risks are significantly impacted by anal intercourse but probably not to the degree needed to drive a generalized HIV epidemic. Anal intercourse likely plays a significant role in HIV infections among a small minority of South
Africans who patronize alcohol serving establishments. Heterosexual anal intercourse, the most risky sexual behavior for HIV transmission, should not be ignored in HIV prevention for South African heterosexuals. However, this relatively infrequent behavior should not become the focus of prevention efforts.
Recommended from our members
Exploring the relationships among food insecurity, alcohol use, and sexual risk taking among men and women living in South African townships
South African townships have among the highest rates of HIV infection in the world. Considerable research on understanding the high rates of HIV transmission in this country has identified alcohol use as a critical factor in driving the HIV epidemic. Although the relationship between alcohol use and sexual risk-taking is well documented, less is known about how other factors, such as food insecurity, might be important in understanding alcohol's role in sexual risk-taking. Furthermore, prior research has highlighted
how patterns of alcohol use and sexual risk-taking tend to vary by gender. We examined how food insecurity is related to both alcohol use and sexual risk-taking. We administered anonymous community surveys to men (n = 1,137) and women (n = 458)
residing within four contiguous Black African townships outside of Cape Town, South Africa. In multivariate linear regression, we found that food insecurity was related to having higher numbers of male sex partners and condom-protected sex acts among
women only. These relationships, however, were fully mediated by women's alcohol use. Among men, we found that food insecurity was negatively related to unprotected sex; that is, men with greater food security reported more unprotected sex acts. Unlike the results found among women, this relationship was not mediated by alcohol use. Food insecurity appears to be an important factor in understanding patterns of sexual risk-taking in regards to gender and alcohol use, and may serve as an important point of intervention for reducing HIV transmission rates.
Recommended from our members
Patterns of alcohol use and sexual behaviors among current drinkers in Cape Town, South Africa
This study examined the association between alcohol use and sexual behaviors among South African adults who reported current drinking. Street-intercept surveys were administered to adults residing in neighbourhoods in a South African township. Analyses were restricted to participants reporting current drinking (N=1285; mean age=32; 27% women; 98% Black). Most participants (60%) reported heavy episodic drinking (i.e., 5 or more drinks on a single occasion) at least once per week in the past 30 days. Compared to non-heavy episodic drinkers, participants who reported heavy episodic drinking were more likely to drink before sex (79% vs. 66%) and have sex with a partner who had been drinking (59% vs. 44%). Overall, drinking before sex (self or partner) and
heavy episodic drinking was associated with multiple sexual partners, discussing condom use with sexual partner(s), and proportion of protected sex. The frequency of condom use varied among participants with steady, casual, or both steady and casual sexual partners. Alcohol use among South African adults is associated with sexual risk behaviors, but this association differs by partner type. Findings suggest the need to strengthen alcohol use components in sexual risk reduction interventions especially for participants with both steady and casual sex partners.
Recommended from our members
Does perceived life stress mediate the association between HIV status and alcohol use?: evidence from adults living in Cape Town, South Africa
South Africa has the highest prevalence of HIV in the world. Because living with HIV is stressful and because alcohol consumption is often used to cope with stress, we examined whether stress mediates the association between HIV status and alcohol use among adults residing in South African townships. Field workers approached pedestrians or patrons of informal alcohol-serving venues (i.e., shebeens) and invited their participation in a survey. Of the 1717 participants (98% Black, 34% women, mean age = 31 years), 82% were HIV-negative, 9% were HIV-positive, and 9% did not know their test result. Participants living with HIV reported greater perceived life stress compared to participants whose HIV status was negative or unknown. Perceived stress was associated with an increase in the frequency of alcohol use (drinking days, intoxication, and drinking in shebeens/taverns). Subsequent analyses showed that stress mediated the association between HIV status and alcohol use. These findings indicate that greater frequency of drinking days, perceived intoxication, and drinking at shebeens was associated with elevated stress levels among participants who were HIV positive. Perceived life stress mediates the association between HIV status and alcohol use. Programs to enhance stress management among HIV-positive South Africans may help to reduce alcohol consumption, which may, in turn, lead to reduced rates of HIV transmission.
- …